1. Field of the Invention
The present invention relates to a valve with an improved piston with an elastomer O-ring intended in particular for the agrifoods and sanitation industries.
2. Description of the Prior Art
Valves for use in the above industries must be designed to avoid all risk of pollution of the liquid passing through the valves by bacteria that can grow within the valves.
Some prior art valves include a piston moving inside a cylindrical seat, the piston being fastened to an operating rod running along the axis of the cylindrical seat and the perimeter of the piston carrying an elastomer O-ring providing the seal between the piston and the cylindrical seat.
In the above type of valve, the elastomer O-ring is a force fit in a trapezoidal cross section groove in the piston. This arrangement has many disadvantages.
The most important of these disadvantages is that the product passing through the valve may become trapped between the groove and the O-ring, which can encourage the growth of bacteria.
Bacteria can also grow to the rear of the O-ring if it is defective (mechanically, chemically, thermally or otherwise).
The object of the present invention is to provide a piston type valve which does not have the above disadvantages and which has advantages of its own.